Drive arrangement for a wiper device for windows of motor vehicles

ABSTRACT

The invention relates to a drive arrangement of a wiper device for windows of motor vehicles with at least two swivel-mounted wiper arms ( 18, 20 ) that are connected to one another via a crank mechanism, wherein one of the wiper arms ( 18 ) is directly coupled with a driven shaft ( 16 ) of an electromotive drive ( 10 ).

The invention relates to a drive arrangement of a wiper device forwindows of motor vehicles with the features cited in thepre-characterizing clause of Patent claim 1.

STATE OF THE ART

Various designs of drive arrangements for windshield wiper devices ofmotor vehicles are known. A known arrangement is comprised of thetransfer of rotary propulsion of an electric motor into a rotatingmovement of a wiper arm axis with two end positions. This transmissiontypically takes place by means of a crank mechanism.

Since most of the time a windshield wiper device is made up of two wiperarms that can be swiveled in a parallel direction, a second wiper arm iscoupled with the first by means of a crank and rocker linkage or thelike. The kinematics of this coupling can take the various paths ofmotion of the two wiper arms into consideration since, to increase thewiper field on the window, oftentimes one of the two wiper armsdescribes a greater slewing angle than the other.

ADVANTAGES OF THE INVENTION

A drive arrangement of a wiper device for windows of motor vehicles inaccordance with the invention includes at least two swivel-mounted wiperarms that are connected to one another via a crank mechanism. With thisarrangement, one of the wiper arms is directly coupled with a drivenshaft of an electromotive drive. It is preferred that this electromotivedrive includes a uniformly transmitting gear. In addition, it is alsopreferred that an electric driving motor of the electromotive drivefeature rotational direction reversal. This rotational directionreversal is responsible for a reversal of the rotational direction ofthe driving motor at each end of travel of the wiper arms.

As compared with a conventional wiper drive, the drive arrangement inaccordance with the invention makes it possible to dispense with oneintermediate gear since one of the wiper arms is directly driven, i.e.,without a non-uniformly transmitting intermediate gear arrangedin-between. The same motor shaft preferably drives the other wiper armin a conventional manner via a non-uniformly transmitting intermediategear. A coupling of the two wiper arm shafts can be accomplished inparticular by means of a crank and rocker linkage so that the wiper armsdescribe a path of motion in the same direction, wherein the paths ofmotion can be parallel to one another depending upon the kinematics.

The electromotive drive preferably features a sensory mechanism todetect the end of travel of the wiper arms. This sensory mechanism canprovide for the required reversal of the rotational direction of thedriving motor. In addition, this type of sensory mechanism is alsosuitable for making speed control of the wiper arms possible. Thus, oneembodiment of the invention can provide for the speed of the wiper armsto be reduced always in the vicinity of the end of travel so that as awhole a harmonic sequence of motion is made possible.

Additional advantages embodiments of the invention are yielded from theremaining features cited in the dependent claims.

DRAWINGS

The invention is explained in more detail in the following in preferredexemplary embodiments on the basis of the associated drawings. Theyshow:

FIG. 1 A depiction of the principle of a drive arrangement for awindshield wiper device in accordance with the invention.

FIG. 2 A schematic top view of the drive arrangement according to FIG.1.

FIG. 3 An example of a speed progression of a wiper arm of the drivearrangement in accordance with the invention.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

An exemplary embodiment of a drive arrangement of a wiper device forwindows of motor vehicles in accordance with the invention isillustrated on the basis of FIGS. 1 and 2. A first wiper arm 18 isconnected to a driven shaft 16 of an electromotive drive 10. This drive10 includes an electric driving motor 12 and a uniformly transmittinggear 14 coupled with it, whose driven shaft 16 drives the first wiperarm 18. Arranged on an opposite, free end of the first wiper arm is afirst wiper blade 22, which travels over the window of the motor vehicle(not shown) in an alternating movement of the wiper arm 18.

The electromotive drive 10 preferably features a sensory mechanism (notshown) to detect the end of travel of the wiper arm 18 and isresponsible for a respective rotational direction reversal of theelectromotive motor 12 at the end of travel, which reversal isrespectively transmitted via the uniformly transmitting gear 14 to thedriven shaft 16.

In addition, the sensory mechanism is preferably in a position toslightly retard the speed of the wiper arm 18 in the vicinity of the twoends of travel in order, if necessary, to make possible a uniformsequence of motion that is gentle to the material.

In addition, a crank 26 is coupled with the driven shaft 16, whichrepresents a lever arm for a crank and rocker linkage 30 that ispositioned on it in an articulated manner.

Another end of the crank and rocker linkage 30 is connected in anarticulated manner with a rocker arm 28, which is coupled with a secondshaft 32. The second shaft 32 is aligned approximately parallel to thedriven shaft 16 and bears a second wiper arm 20, on whose free end asecond wiper blade 24 is arranged. The crank mechanism, which is made upof the crank 26, the crank and rocker linkage 30 and the rocker arm 28,is responsible for transmitting the rotating movements of the drivenshaft 16 to the second shaft 32 and therefore to the second wiper arm20.

Depending upon the desired paths of motion, the crank 26 and the rockerarm 28 can feature lever arms of different lengths so that, for example,the first wiper arm 18 can feature a pivoting angle of 110 degrees andthe second wiper arm 20 can feature one of only 95 degrees. It is alsopossible to set a permanent angle offset of the two wiper arms 18 and 20via the length of the crank and rocker linkage 30 in relation to thedistance of the two shafts 16 and 32.

The drive arrangement in accordance with the invention makes it possibleto dispense with a non-uniformly transmitting gear between the drivingmotor 12 and the driven shaft 16, as is required in the case ofconventional wiper drives. The uniformly transmitting gear 14 mustmerely provide for a speed adjustment and can therefore be considerablymore compact than a non-uniformly transmitting gear. Structural spacecan be saved depending upon the available space conditions in thevehicle.

With the electronics that are available today, an electronic reversal ofthe rotational direction can be obtained in a very simple and reliablemanner. This type of electronic control of the rotating movements isclearly more cost effective than using mechanical parts like anon-uniformly transmitting gear.

FIG. 3 illustrates a qualitative speed diagram of one of the two wiperarms 18 or 20, which is slowed at each of its two ends of travel E1 andE2 in order to enable the most uniform possible rotating movement of thewiper arms that is gentle to the material. In this case, the x-axisshows time t and the y-axis shows the rotating speed v of one of the twoshafts 16 or 32, each in a qualitative representation. One reversal ofthe rotational direction (not shown) is provided for when passingthrough each of the ends of travel E1 and E2.

1. Drive arrangement of a wiper device for windows of motor vehicleswith at least two swivel-mounted wiper arms (18, 20) that are connectedto one another via a crank mechanism, wherein one of the wiper arms (18)is directly coupled with a driven shaft (16) of an electromotive drive(10).
 2. Drive arrangement according to claim 1, characterized in thatthe electromotive drive (10) includes a uniformly transmitting gear(14).
 3. Drive arrangement according to claim 1, characterized in thatan electric driving motor (12) of the drive (10) features rotationaldirection reversal.
 4. Drive arrangement according to claim 3,characterized in that a reversal of the rotational direction of theelectromotive drive (10) is provided for at each end of travel of thewiper arms (18, 20).
 5. Drive arrangement according to claim 1,characterized in that the electromotive drive (10) features a sensorymechanism to detect the end of travel.
 6. Drive arrangement according toclaim 1, characterized in that the electromotive drive (10) features aspeed control.
 7. Drive arrangement according to claim 6, characterizedin that the speed control always provides for a reduction in therotational speed of the drive (10) near the ends of travel of the wiperarms (18, 20).
 8. Drive arrangement according to claim 1, characterizedin that at least two wiper arms (18, 20) are coupled via a crank androcker linkage (30).
 9. Drive arrangement according to claim 8,characterized in that both of the wiper arms (18, 20) feature a path ofmotion in the same direction.
 10. Drive arrangement according to claim1, characterized in that at least two wiper arms (18, 20) feature anapproximately parallel path of motion.
 11. Drive arrangement accordingto claim 2, characterized in that an electric driving motor (12) of thedrive (10) features rotational direction reversal.
 12. Drive arrangementaccording to claim 11, characterized in that a reversal of therotational direction of the electromotive drive (10) is provided for ateach end of travel of the wiper arms (18, 20).
 13. Drive arrangementaccording to claim 11, characterized in that the electromotive drive(10) features a sensory mechanism to detect the end of travel.
 14. Drivearrangement according to claim 13, characterized in that theelectromotive drive (10) features a speed control.
 15. Drive arrangementaccording to claim 14, characterized in that the speed control alwaysprovides for a reduction in the rotational speed of the drive (10) nearthe ends of travel of the wiper arms (18, 20).
 16. Drive arrangementaccording to claim 14, characterized in that at least two wiper arms(18, 20) are coupled via a crank and rocker linkage (30).
 17. Drivearrangement according to claim 16, characterized in that both of thewiper arms (18, 20) feature a path of motion in the same direction. 18.Drive arrangement according to claim 16, characterized in that at leasttwo wiper arms (18, 20) feature an approximately parallel path ofmotion.
 19. Drive arrangement according to claim 18, characterized inthat a reversal of the rotational direction of the electromotive drive(10) is provided for at each end of travel of the wiper arms (18, 20),the speed control always provides for a reduction in the rotationalspeed of the drive (10) near the ends of travel of the wiper arms (18,20), and both of the wiper arms (18, 20) feature a path of motion in thesame direction.